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Toyota Highlander Hybrid Transmission Questions

PF_FlyerPF_Flyer Pennsylvania Furnace, PAPosts: 8,769
Having an issue or a question about your THH transmission? This is the place to aks!

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  • phoebeisisphoebeisis Posts: 121
    Is there any sort of fluid coupling on the HH CVT Transmission?If not,then this certainly gives it another edge in hy mpg over the regular Highlander.Using the fluid to transfer power is a big energy waster.Maybe someone could point me in the right direction-or even give a short seminar on the Toyota CVT?Thanks.Charlie(using fluid to assist a shift is fine,but using it to do the power transfer isn't)
  • kcreadykcready Posts: 7
    Has anyone had experience storing their HH for extended periods of time?
    I would be storing it for 3 to 4 months a year. I have been told by the dealer that there is an inexpensive small charger that would keep the traction battries up. Anyone know anything about it?
  • gazguzlergazguzler Posts: 137
    That battery charger would be very interesting (if true) because this would turn the HH into a plug in hybrid.

    Please keep us posted if you get any solution for this. This would be very exciting.

    Also, I don't like the center console on my LTD. After the shift lever it's a huge bulky thing that's pretty much useless (at least to me). I'd rather have a fridge. I see in some RX300s and older Hs that there were other designs including one that has two separate pieces: one a wrap-around for the shifter and the other the cup and cd holder, which looks easy to take out and I could put the fridge there.

    Are all the center consoles the same for HHs or 05 Highlanders, does anyone know. .
  • landdriverlanddriver Posts: 607
    The stand-alone console configuration you described is only present in '01 HLs (and some '02 Canadian HLs). Actually the separate console piece was an option -- '01 HLs simply had an open space in this area where you could put your briefcase or purse, or use it to step through to the back seat area. But since '02 there has only been the integrated console configuration.

    I actually retrofitted an '02 integrated console into my originally consoleless '01 by purchasing the individual parts from the Toyota parts department, so it may be possible to go the other way, although you'll have some holes in the carpet to deal with. You'll have to buy that wrap-around piece for the shifter and a new plastic bezel that frames the gear shifter; the wrap-around piece will be available in the same color but probably not the bezel, but I know there are apparently aftermarket kits for upgrading all the interior trim pieces, so you may be able to get everying to match up.

    (Good to know you're not one of those guys who try to blow people away at stop lights.)

    Where did that photo of the HL in the swimming pool come from???!!!
  • nimhrodnimhrod Posts: 49
    That's an HL? No kidding, from the top it looks like a minivan.
  • gazguzlergazguzler Posts: 137
    Thanks for all the info. I really want the wrap-around for the shifter and nothing else. I ripped out the center of my 4Runner and put an electric fridge there and that, my friends, is heaven. Vector makes these great ones that fit right with an elbow pad.

    I found the photo on the next. Seems by the credit that it's from a Hawaii newspaper. It's definitely a HL because of the corrugated roof. That the refracted light makes it look like a minivan gets to the painful issue of what is it, anyway? Because it's not a real SUV :-)
  • toyotakentoyotaken Posts: 897
    There is no true CVT in the HH. There is a direct drive from the electic motors to the wheels. MG1 and/or MGr are the drive motors and are driven either from power from the NIMH batteries or a combination of the batteries and the ICE engine. In either case, there is no true transmission, conventional or otherwise in the vehicle.

    Hope this helps.

  • sunbyrnesunbyrne Posts: 210
    Well, it's not *just* the drive motors--the power is "merged" via a planetary gear mechanism. See

    It's a little weird. I've not driven other cars with traditional CVTs, but the complete lack of shifting in the HH is slightly strange at first, then quite appealing. I still actually prefer a manual, but if you're not going to have one, why shift at all, right?
  • toyotakentoyotaken Posts: 897
    That's true, but a bit more involved in explaining... Mainly wanted to convey that there isn't a "real" CVT in the HH more than anything else. But thank you for clarifying for those who are a bit more "technically inclined"

  • Anyone out there in HH country experiencing the same kind of transmission problems that plague regular Highlanders? That is, a serious and dangerous delay when the gas pedal is pushed down? Some try pushing and releasing the gas pedal quickly. In my Highlander, the vehicle will not even raise one rpm. It will just sit and idle. I can push the gas ten times and nothing. The delay is maddening.
  • 650vac650vac Posts: 26
    Not yet, I only have 1,300 miles on the vehicle. If it is the transmission, I believe the two aren't of the same design.
    What has the dealer said? I would think if it truly were a transmission problem, the car might not move but the rpms would go up.
  • HH transmission is completely different than gas models (continuously variable, no discrete gears), plus the way the computer uses the electric motor and gas engine there's immediate and pretty impressive accelleration - the opposite of hesitation for sure.

    In park every once in a while we experience a jump when the ICE kicks in - most noticeable in the garage - so I've learned to set the parking brake always (yes, I should have but never did with other automatic cars, my wife got used to it driving a stick).

    If there were similarly described problems they wouldn't have a common cause in the transmission. - John
  • "In park every once in a while we experience a jump when the ICE kicks in - most noticeable in the garage - so I've learned to set the parking brake always (yes, I should have but never did with other automatic cars, my wife got used to it driving a stick)."

    I've had this happen as well. I think that this is a safety problem. If I'm in Park or even in Drive with my foot on the brake, having the ICE start should NOT cause a buck.
  • This is in relation to a post I made a few days back in relation to my 2001 HL that was involved in a front end, partly left colission. Since after the accident, the car has had hesitancy problems but only when backing up; forward, it runs beautifully(transmission was in very good condition prior to accident). Dealership wants to tear up the transmission to find out what exactly happened and to determine if damage was a result of the accident in which case insurance will pay. But if not then we pay. Any opinion in this matter will be deeply appreciated.
  • wwestwwest Posts: 10,706
    and then there are CVT's,... NOT!

    The more "conventional" CVT uses a dual pulley belt drive wherein the ratio of one pulley vs the other is continuously variable.

    The "CVT" in the various hybrid models varies so widely from "convention" that it should NEVER be referred to as a CVT.

    The ICE output shaft drives, directly, both a motor/generator/starter assembly (MG1) and the input shaft to a planetary gearset. The "other" "input" to the planetary gearset is yet another motor/generator (MG2). The output shaft of the planetary gearset goes to the drive wheels.

    Think of it this way:

    The output of MG2 is coupled to a 3:1 gear reduction assembly and then that output is coupled in turn to the one of two input drive shafts of an open differential. Then the combined output of the ICE and MG1, operating logically in parallel, are coupled to the other input shaft of the open differential. The output shaft of the open diff'l is used to drive the driven wheels.

    An example...

    Jack up the rear of a RWD with a standard rear open diff'l so both wheels are off the ground and put the manual transmission in neutral. Station yourself on the driver's side rear wheel and I'll handle the other side, you're the ICE/MG1 and I'll be MG2. Now start turning your wheel as if the ICE were started up and idling. We don't yet want the "output" shaft (drive shaft) to start driving the wheels so I begin turning my "wheel" in synchronization with yours but in opposition so as to prevent any movement of the drive shaft.

    So, you, the ICE/MG1, can turn your "wheel", input to the open differential, as fast as is possible and as long as I (MG2) can keep in synchronization our "CVT" remains in neutral.

    Want the output shaft to drive us forward, I'll just slow my rotation rate. Want to go even faster? Go WOT with the "ICE" while I hold my wheel steady. Want to go 0-60 in quicktime? Now I start "forcefully" turning my "wheel" in the direction that aids the "ICE" input.

    But wait, the ICE can produce a LOT more torque than MG2, especially in the higher RPM ranges, why doesn't the ICE, via the open differential, simply drive MG2 "backwards".

    Aha, that's where the planetary gearset comes into play.

    But first, an "aside". That's exactly what happens when I want have the ICE "drive" MG2 now acting as a generator to charge the hybrid battery.

    Instead of me at the opposite wheel lets put a 100 lb weakling with say, 1/3 of the muscle (torque) needed to overcome the level of effort (torque) you can apply on your (ICE/MG1) end.

    And now level the "playing" field by giving our weakling a 3:1 gear reduction between the wheel and the input to the open diff'l.

    Now the weakling can provide an equal level of torque to the diff'l as can the ICE/MG1, even with the ICE/MG1 turning at 5500 RPM at WOT.

    Oh, did I mention that it is a very simple matter for MG2 to rotate at 15,000 RPM in order to keep "pace" with the ICE/MG1 at 5500?

    Magic, BLACK magic..
  • You are very smart. But can you explain everything that you said in plain English?
  • Can anyone explain to me the difference between AWDi and AWD My Limited has AWDi I noticed other highlanders only have AWD, no i after letters. What is so different about this mode. Did anyone ever try both kinds and noticed any difference? Also speaking of traction my wife's buick has traction control, How is this different than AWDi. I hope someone can explain these various modes to me. Thank you in Advance Frank
  • wwestwwest Posts: 10,706
    Just guessing, but my guess is that "AWDi" is simply the label Toyota applies to the HH version to differentiate it in customer minds from the standard Highlander.

    Probably another play on "i", for intelligence, since the rear wheels on the HH are only driven by MG3 in certain situations, such as front wheelspin/slip or hard, WOT, acceleration below ~20 MPH.

    Whereas the standard Highlander uses a mechanical coupling from the transaxle to the rear diff'l. In which case no "thinking" (intelligence) is required.

    For those standard AWD Highlanders not equipped with the VC that means you do not have rear drive unless you hear the brakes "rattling" as they brake the front "slipping" wheels in an attempt to reapportion engine drive torque to the rear.

    Not that the early inceptions of the VC in the RX/HL were all that good, they weren't, and the vote is still out on the new VC design in the RX350 and....
  • cdptrapcdptrap Posts: 485
    This is my understanding, others will surely chime in. The HH is our first car with AWD ( or AWDi). We have always had one or two workhorse 4x4.

    Our HH actually says 4WDi, not AWDi. May be later model Highlander Hybrid has different badging?

    AWD is a much abused term. To do it justice, we need to distinguish between full-time AWD and part-time or on-demand AWD. AWD in general means the car powers all four wheels. Full-time AWD means the four wheels receive power all the time. On-demand still means the driver can decide, by flipping a switch, when to put power into all four wheels. All such AWD require some mechanical linkage to transmit power generated by the engine all the way into each wheel. I will get to AWDi yet :)...

    AWD is not always 4WD. 4WD or 4x4 generally has a low-range for low speed high torque driving. They are great for taking on challenging terrain. There are other tough mechanical components that make 4x4 different than a normal AWD. Newer and more expensive AWD systems (Mercedes, Lexus, Subaru?) are now appearing that brings AWD a little closer to mainstream 4x4 but that is another whole discussion.

    The HH is really not an AWD or a 4WD because it does not supply power to the rear wheels all the time. It is a sophisticated automatic on-demand part-time AWD. The HH is really a FWD most of the time. The on-board computer decides when power in the rear is needed and activates the rear electric motor to drive the rear wheels only when necessary. We as drivers have no say as to when to pop into AWD and when to pop out of AWD. The car decides on its own. This may be why Toyota added the "i" to denote "Intelligent".

    In our HH, we notice that it activates the rear motor to drive the rear wheels during hard acceleration or when it needs power to climb a steep grade at low speed. And of course, it uses the rear wheels to help recharge the batteries.

    How AWD and AWDi and 4x4 tie into modern Traction Control is in removing and applying power to all four wheels. Instead of having just 2 drive-wheels (as in FWD or RWD), it now has 4 drive-wheels with which to maintain control. So the Traction Control system can now decide which wheel is losing traction and spinning, brake that wheel as appropriate and also remove power from that wheel. The system can then transfer power to other wheels that are not spinning and still have traction. This is nice because having more powered wheels with traction allows the driver to more easily maintain directional control.

    The AWDi version of the HH integrates its AWD system "intelligently" (we pray and hope) with its Traction Control. If it detects one of the front drive wheels losing traction, it will automatically activate the rear motor to provide power to the rear so whichever rear wheel that has traction will get power. A kind of instant AWD+Traction Control magic. Thus the "4WDi" or "AWDi" badge.

    Do know that the best Traction Control cannot out-perform the tires. Cheap slippery tires or tires with low tread height will lose traction sooner and can result in dangerous accidents even with Traction Control. I watched a friend's 4WD SUV with Traction Control slowly slipped off a snowy icy road (in the Sierra mountains) into a shallow ditch because the tires could not provide enough grip and he refused to put on chains. Our FWD van, with *no* traction control but with chains on the front tires made it down the same road just fine. Get good tires and bring chains even when you have an AWD and Traction Control.

    Hope this helps and I hope I did not make stupid mistakes and told you any wrong thing. :)
  • A car has 4 wheels, right? So when someone says "AWD", doesn't it mean "all 4 wheels"? In the same context, shouldn't it mean "all 4 wheels" when someone says 4WD? So what's the difference? :cry:
  • terry92270terry92270 Posts: 1,247
    In 4 Wheel drive, like the old Jeeps, actually had to get out, lock the hubs on the axle, to get it. It was equally divided among the four feels.

    AWD is, or was, generally capable of four wheel drive, wherein the computer and sensors transferred power to all four wheels, on demand, as needed, in various percentages.

    Most other descriptors are merely marketing ploys, and not technology. ;)

    It could have better been presented to the public as On Demand 4 Wheel Drive, not "just" AWD.
  • cdptrapcdptrap Posts: 485
    I wish whoever invented these terms were more careful. This is how I see the differences after years of driving 4x4 or 4WD as it was originally defined.

    4WD or 4x4 normally has a locking differential, solid axles and springs and shocks that gives a lot of room for the tires to "extend". Such a car can put power to all 4 wheels and also has tranmission gearing that offers 4 High and 4 Low.

    Locking differential, when locked (manually), allows all four wheels to turn at the same speed with absolutely no chance of any wheel spinning free. When it is not locked, one wheel can often turn faster or slower than another wheel depending on terrain and driving condition. This allows spinning to occur. Spinning, at least in my experience, causes problems because when a tire spins on a smooth surface (boulder, rock, sand), it is not helping my truck to move along the trail. While the wheel on the other side of the spinning wheel can still work if it has traction, it now has actually less power to use to move things along. Spinning also causes jerks and slips and slides, all very very bad on rough terrain that requires precise control. With a fully locked diff, the tires must move at the same speed. So the tire with less traction still must move at the same rate as the tire with traction. It really keeps my truck moving nicely especially when I am a bit tilted and having to drive on the side of a rock (off-camber?). I used to do a lot of work on farms and ranches, so we learnt these things from old-hands who passed along their knowledge.

    This is why in demanding off-road condition, we prefer fully locked differential, not the popular "Llimited Slip Differential" which still allows the wheels to move at different speed. With power into all 4 wheels and the locker, the car can really do some crawling with authority.

    4 High in general refers to the normal gearing we use for everyday on-road driving. 4 Low is the low speed, high torque gearing we use when we have to haul a really heavy load or when we have to negotiate really nasty terrain at low speed. We will lock the differential, shift into 4-Low and work our way through rocks, deep ruts, sometimes mud (not always) or deep snow and so on at low speed.

    Run-of-the-mill AWD in general does not offer locker, does not offer solid axles and does not offer 4-low. While it still powers all 4 wheels, it is not capable of heavy duty hauling or demanding off-road work. Such AWD system is either part-time automatic or full-time requiring no driver input. That means you do not have to jump out to lock the hubs. On paved surface, this capability does make the car safer especially when integrated with modern Traction Control; so everyone is selling some form of AWD for on-road use.

    Another way to see this is that while 4x4 uses a locking differential and low gear to provide "Traction Control" and eliminate wheel spin, AWD uses power-reduction and Anti-lock brakes to eliminate spin in a wheel.

    New generation AWD (Lexus, Mercedes, Land Rover, Ford, Jeep, etc) now offers some form of low-gearing in some of their AWD models. I recall seeing a SUV in the 80's (Ford Explorer?) that had switches on the dash that switched between 4Hi and 4Lo.

    Amidst all these confusing marketing terms, I now use the terms "4 by 4" or "4x4" to mean the real-life old style truck that offers locker, 4Lo. Everything else is some form of AWD. When talking to salesman, I ask very specific question to be sure we are talking about the same thing. It is pays to actually see the car and actually ask where is the 4Lo? Where are the hubs?

    The 4WD-i HH is definitely not a full-time AWD or 4WD or 4x4. It is a FWD first and automatic on-demand AWD second.
  • wwestwwest Posts: 10,706
    Is that AWD never requires driver intervention, should really be referred to as AAWD, Automatic All Wheel Drive.

    And sorry, there can never be, WILL never be, an otherwise satisfactory definition of AWD, 'way to many variations in the design methods for impleenting AWD, SH-AWD likely being at the top of the list insofar as functionality, and those with a simple open center differential with brakes used to apportion engine torque being at the bottom.
  • stevedebistevedebi LAPosts: 4,098
    "The more "conventional" CVT uses a dual pulley belt drive wherein the ratio of one pulley vs the other is continuously variable."

    Close, but no cigar. The good quality CVTs use a chain, not a belt.
  • wwestwwest Posts: 10,706
    Sorry, can't agree, exactly, it IS a metal "belt", metal to metal friction drive, not a metal "chain".

    I don't exactly disagree with calling it a metal chain, just that it conveys the wrong impression for most readers.
  • stevedebistevedebi LAPosts: 4,098
    "I don't exactly disagree with calling it a metal chain, just that it conveys the wrong impression for most readers."

    Well, the word "belt" conjures up the image of a timing or pully belt in the engine compartment. That is a lot less durable than high strength steel.
  • wwestwwest Posts: 10,706

    Age differences have struck again.

    To me, belt, when used in an automotive context, relates to fan belt or serpentine belt, completely over-looked the ribbed or cogged timing belt.
  • Don't try driving your HH AWDi on ice. We ahve a big hill near our house and unless you get a running start, the HH will quit 1/2 way up and slide uncontrollable backwards. The AWDi/traction control just stops work when all the wheels start slipping. Since there is no "low" gear, the transmission just wants to accelerate and cuts off when it sense the RPMs are too high and there is not traction.

    Being the cynic I am, I think this was done so Toyota will not have electric motor/transmission problem that would be covered in their 100,000 mile electrical drivetrain warranty. Sheetmetal and structural damage is covered by the owner!
  • cdptrapcdptrap Posts: 485
    Wow, you hit a worst case scenario where all four tires lose all traction. THANKS for sharing the experience. Do you have snow tires on your HH? I am just wondering if good snow tires will make a difference. We got our set of four snow tires but we have not put them onto our HH. Sounds like I have better do it.

    I believe when there is a total loss of traction, not even a HUMMER can do much but slide. We have had some interesting experience in our 4x4 V8 Chevy on tall wet grass. 4x4 or not, low gear or not, once the 4 tires lose all traction, the truck will slowly but surely slide backward. We used to have a 4x4 Jeep with a rear mount post-hole digger (used car purchase) for digging fence posts. After that thing slipped and slid down a steep grassy slope, we ended up calling the pros. They came in with a tracked vehicle. I guess when the "HUMMER" cannot do it, it is time for the M-1's :).
  • stevedebistevedebi LAPosts: 4,098
    "Don't try driving your HH AWDi on ice. We ahve a big hill near our house and unless you get a running start, the HH will quit 1/2 way up and slide uncontrollable backwards. The AWDi/traction control just stops work when all the wheels start slipping. Since there is no "low" gear, the transmission just wants to accelerate and cuts off when it sense the RPMs are too high and there is not traction."

    I suppose it is on another HH topic, but this has been discussed recently. The TC will stop the wheels from moving; overheating the AWD electric rear motors will stop the AWD from working.

    Yes, Toyota is preventing the components from burning out. The HH AWD is not meant for anything resembling off-road use, which I guess also includes your icy climb.
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